Cable connector



Dec. 5, 1939. J w HOFMANN 2,182,151

CABLE CONNECTOR Filed Oct. 7, 1936 iNVENTOR yohannes mlbelm Jiof'malln BY WW ATTO R N EY Patented Dec. 5,1939

UNITED STATES PATENT OFFICE CABLE CONNECTOR Johannes Wilhelm H'ofmann,

Radebeul-Kotz- Application October 7, 1936, Serial No. 104,446 In Germany October 16, 1935 1 Claim.

This invention relates to cable connectors and more particularly relates to connectors for automatically maintaining the clamping pressure between the jaws of the connector and cable where 5 cross-sectional yielding of the conductor occurs.

Aluminum cables have come into extensive use, and prior connectors for cables were unsatisfactory due to the relatively high ductility of the aluminum. The clamping pressures of the connector jaws resulted in a cross-sectional yielding and compression of the aluminum cable, reducing the cross-sectional area. Although the, prior connectors were satisfactory for copper cables, they failed with the light weight conductors because of the relative .ease of compressibility of such conductors.

The contact resistance between an aluminum cable and the connector increases when the cable is compressed due to the reduction in the contact pressure. The increased contact resistance results in heating at the connector joint, which adds to the ductility of the metal to further in- I crease the yielding by the cable. Alternate warming and cooling of the conductor due to varying load current conditions aggravates this phenomenon until the connection is finally destroyed by fusing.

Faults are expensive to repair, particularly in crowded and heavily loaded networks. Prior clamps, designed with transverse jaws tightened together by bolt and nut, required periodic tightening to maintain the contact pressure at the connection to prevent fusing Spring washers were inserted between the bolts and jaws in an attempt to maintain the clamping pressure constant. However, the washers were unsatisfactory since they limited the requisite high clamping pressures.

In accordance with this invention, one or more of the jaws of the cable connector are designed as elastic or compliant members. The compliant jaw automatically adjusts itself to any varying cross-sectional conditions of the conductors to maintain the contact pressure with the cable substantially constant. Fusing and faults are obviated since the contact resistance and contact pressure at the cable connection is unafiected by changes in the cross-sectional area of the cable as in prior devices. The cable connector of this invention automatically compensates for varying conditions and requires no attention after it is installed and is accordingly particularly suitable for inaccessible and underground cable constructions. The connector may be used to join two dissimilar conductors, for example copper and aluminum, without deleterious corrosive efiects.

It is accordingly an object of this invention to provide a novel connector particularly useful for light weight conductors such as aluminum.

It is another object of this invention to pro- 5 vide a novel cable connector having compliant jaw members.

It is a further object of this invention to provide a novel cable connector which joins cables of varying shapes and cross-sections and auto- 10 matically maintains the contact resistance and pressure at the connection substantially constant.

It is still a further object of this invention to provide a novel cable connector for joining two cables of different metals such as copper and 15 aluminum. I

These and other objects of the invention will become evident in the following description of several modifications taken in connection with the drawing, in which: 20

Figure 1 is a modification of one embodiment of the cable connector showing one compliant jaw member.

Figure 2 is a side view further illustrating the modification of Figure 1. 5

Figure 3 is an end view of another modification for a cable connector in accordance with this invention; and I Figure 4 is a side view of the modification of Figure 3. v 30 Figure 5 is an end view of a. modified form of the cable connector having two compliant members; and

Figure 6 is a side view of the modification of Figure 5. x 35 Referring to Figures 1 and 2, a modification of the invention is illustrated for mechanically and electrically connecting a branch feeder ill to a main cable H having a larger cross-sectional area than cable l0. These cables are illustrated as 40 stranded conductors, cable I0 having a circular section and'cable I I a triangular section. It is to be understood that the connectors of the present invention may be readily designed by those skilled in the art to be applicable for conductors of equal or different dimensions and cross-sectional configurations.

Clamp jaws l2 and I3 are secured in position over the cables l0 and II by screw members I4 50 which pass through screw holes or circular openings IS in jaw member l2 and are anchored in jaw member l3 at the threaded portions [6 thereof. A central pressure plate I! is provided to mechanically separate the two conductor 55 cables I and H and to equalize the pressures upon each cable.

The jaw members l2 and i3 and the pressure plate H are provided with'longitudinal grooves or arched seat corresponding to the configuration and size of the co-acting conductor portions in contact therewith. It has been found that for stranded cables, the longitudinal grooves co-acting with the cables need not be serrated to maintain the mechanical connection for cables under tension. However, serrations may be added is well known in the art.

The pressure plate I! is not attached to the jaw or screw members, but is floatingly suspended between the cables l0 and II and the screws I4. Projections l8 extend from pressure plate H at the screws Hi to guide the plate vertically and prevent dislodgement thereof. Plate I1 adjusts itself in proper position between the jaws and conductors and transmits and equalizes the pressure between the cables between the opposed jaws l2 and I3.

This invention particularly resides in the provision of the compliant jaw member l2 for the cable connector. The outer portions or wings 19 of the jaw l2 are provided with holes I having a diameter larger than the screw l6, but smaller than the head 20 of screw I4. The compliant jaw 12 is made of a metal having a high elasticity and may be a suitable steel, bronze or heat-treated aluminum alloy.

The unassembled shape of compliant member I2 is shown somewhat exaggerated by the dotted position. In assembling the connector, the screw heads 20 tighten down upon wings l9 until a suitable pressure exists between the jaws and the cables. Jaw I2 is designed with sufficient crosssectional area and elasticity so that it is still under elastic deformation under the maximum screw pressure exerted in the field. Accordingly, member I2 is designed with a normal W shape shown by the dotted position so that after assembly the wings I9 will assume a somewhat level position as illustrated. A relative movement occurs between the wings l9 and the screw heads 20. Accordingly, the screw holes I5 in wings iii are made of sufficient diameter to permit this movement and the wings l9 are somewhat curved as shown to permit the relative sliding with minimum frictional impedance.

The assembled cable connector as illustrated in Figure 1 provides the requisite mechanical pressure for maintaining the cables Ill and I I in position and also serves as an electrical connection between the cables. Member l2, elastically deformed when, assembled, maintains the requisite pressure between cables l0 and II and the pressure plate I! floatingly inserted therebetween. Any contraction in the cross-sectional area of the cables in or II or both will be instantly compensated for by the compliant jaw l2, the central portion 2| of which will move against cable ID as will now be evident to those skilled in the art. Jaw l2 acts as a compressed spring against the cables and any slight contraction in the cables will be followed by the spring-like action of the central elastically stressed portion 2|. An important advantage of the construction of this invention resides in that the compensation instantly and automatically occurs irrespective of whether cable ID or cable H or both yield. The pressure plate I! being fioatingly suspended between the screws I4, adjusts itself vertically and maintains-an equalized pressure between the cables l0 and H. The lip projections l8 of the plate H around screws M prevent transverse displacement of the plate.

Referring now to Figures 3 and 4, a modified form of the invention is illustrated. The conductors 22 and 23 are shown as circular but of diflerent sizes. The jaw members 24 and 25 are assembled together with the bolts 26 in a manner similar to the hereinabove described modification. Bolts 26 are shown in position with the nuts 21 co-acting against the flat rectangularly shaped rigid jaw 24; The floating pressure plate 28 corresponds exactly to the plate ll of Figures 1 and 2, and has longitudinal grooves to conform with the conductors 22 and 23. The jaw member 25 in this modification is the compliant member corresponding-to the jaw l2 of Figures 1 and 2. The dotted shape of jaw 25 illustrates its original form before bolting into position. The wings 29 of jaw 25 are preferably designed to be horizontally disposed after tightening and assembling as shown. The central portion 30 of jaw 25 is, in this modification, elastically stressed against the conductor 23 to provide the same action as al-- bolts 35. Jaw 33 is shown similar to jaw l2- of Figures 1 and 2; and jaw 34, to jaw 29 of Figures 3 and 4. The compliant jaws 33 and 34 co-jointly perform the functions of the individual jaws of the other modifications and provide greater elastic compensation than the other modifications.

The cable connector of this invention may be.

usedto join two dissimilar metallic conductors such as copper and aluminum. Corrosive effects between the cables may be eliminated by using a neutral metallic floating pressure plate between thenn The plate-could be constructed of two metals such as copper and aluminum to contact the conductors for preventing corrosive action therebetween.

Although several modifications of the present invention have been illustrated and described, other modifications are feasible which fall within the broader spirit and scope of this invention; and accordingly, this invention is not intended to be limited except as set forth in the following claim.

What is claimed is:

In an electrical connector for electrically and mechanically clamping one cable to another cable, having two opposed clamping plates with clamping means positioned "on each side of the cables clamped in the connector, a clamping plate made of. sheet metal of uniform thickness and having a centrally formed cable engaging arched seat with outwardly extending wingportions integral therewith for engagement with the clamping means adjacent the ends thereof, thereby providing between said arched seat and said wing portions, sections having suflicient resiliency'to compensate for changes in dimensions of the cable supported in the electrical connector, and means associated with said wings providing for relative movement between the clamping means and said wings during the flexing movementof the wings.

JOHANNES WILHELM HOFMANN. 

